This paper from the Netherland presented the development of a national indication protocol for proton therapy (NIPP) for model-based selection of breast cancer patients and reported the clinical experiences. The model of Darby et al. (N Engl J Med 2013; 368:987-82) was used for estimation of the relative risk of an acute coronary event (ACE) based on the mean heart dose. Based on a threshold value of a 2% absolute lower risk on ACE for proton therapy compared with photons, 268 breast cancer patients have been treated in the Netherlands with proton therapy between February 2019 and January 2021